[unreadable] Human Immunodeficiency Virus/Acquired Immuno-Deficiency Syndrome (HIV/AIDS) is an intractable health problem that has defied over 20 years of concerted approaches from a wide range of disciplines. In fact, despite massive multisectoral attempts to prevent its spread, HIV incidence continues to increase around the globe. Youth (young people between the ages of 15 and 24), and particularly female youth, are at greatest risk for HIV acquisition. As sexually transmitted infections (STIs) in general, and HIV in particular, have become inextricably woven together and exacerbated by issues such as poverty, migration, labor market opportunities, and gender-based power disparities, it has become clear that any effective prevention program must address the underlying structural factors which shape individuals' vulnerability, most notably the economic circumstances that condition their risk-taking choices. What is needed is a truly interdisciplinary approach that integrates existing knowledge about youth HIV/AIDS risk behavior to generate new paradigms of risk behavior, and that will foster new approaches to the development and evaluation of effective interventions to prevent the spread of HIV/AIDS among youth. [unreadable] [unreadable] We propose to integrate theoretical, methodological and analytical aspects of the Economic Sciences, Population Sciences, and Behavioral Sciences to develop new pathways to discovery and intervention in youth vulnerability to HIV/AIDS, STIs, and unintended pregnancies. In particular, we aim to understand how structural factors such as poverty, gender-based power, labor market opportunities, and migration ultimately shape these outcomes. The ultimate goal of this work is to develop effective interventions for the prevention of HIV, STIs, and unintended pregnancies. We will develop this new discipline, called Behavioral Economic Epidemiology (BEE), through a three-year process of structured learning and critique of each others' disciplines, focused integration of theoretical models and methods, and validation and pilot-testing of tools and analytic methods. We will also explore strategies for expanding this new approach into a more formalized and enduring discipline by developing a sustainable market for its production and consumption. [unreadable] [unreadable]